Patent GB-952493-A (GB)
Title: Improvements relating to the formation of metal coatings and to the production of joints therewith
Inventor: GAINSBURY PETER EDWARD
IPC: C04B41/51
Filed: 1961-02-21
Abstract: In a process of joining ceramic to ceramic or ceramic to metal a suspension of a Pt group flake metal powder in a liquid which will volatilize or decompose under heat is interposed between the parts to be joined and then sintered. The metal parts may be stainless steel, Cr, Ni, Mo, Nb, Re, W, Ta or Ti and the ceramic parts may be alumina or zirconia either glazed or unglazed.  The liquid dispersant may be water or preferably a resin dissolved in an organic solvent, such as a solution of condensed methyl cyclohexane polymer in 2-ethoxy ethanol, diacetone alcohol or 2-ethoxyacetate, or it may be a metal bearing liquid such as the liquid bright metals containing Pt, Au or Ag, e.g. gold tertiary dodecyl mercaptan.  The flake powder forms 10-90% by weight of the dispersion which may also contain glass powder which helps the bonding of the metal flake to the ceramic part. In the case of ceramic it is preferable to first metallize the ceramic by thermal decomposition of a metal bearing liquid such as the reaction product of chloroplatinic acid and di-iso-propyl ether or gold-tertiary dodecyl mercaptan. Specifications 878,821 and 878,822 are referred to.ALSO:A metallic or ceramic base is coated with a Pt group metal by applying the coating as a suspension of the flake metal powder in a liquid which will volatilize or decompose under heat and sintering the coating.  The metal base may be stainless steel, Cr, Ni, Mo, Nb, Re, W, Ta or Ti, and the ceramic may be alumina either glazed or unglazed, or zirconia.  The liquid dispersant may be water or preferably a resin dissolved in an organic solvent, such as a solution of condensed methyl cyclohexanone polymer in 2-ethoxy ethanol, diacetone alcohol or 2-ethoxy acetate, or it may be a metal bearing liquid such as the liquid bright metals containing Pt, Au, or Ag, e.g. gold tertiary-dodecylmercaptan. The flake powder forms 10-90% weight of the dispersion which may also contain glass powder which helps the bonding of the metal flake to the ceramic base.  Sintering of the coating is effected at a temperature of at least 800 DEG C., in a reducing or neutral atmosphere for a metal base and an oxidizing or neutral atmosphere for a ceramic base.  In the case of a ceramic base it is preferable to first metallize the ceramic by the thermal decomposition of a metal bearing liquid such as the reaction product of chloroplatinic acid and diiso-propyl ether or gold tertiary dodecyl mercaptan. By dispersing the flake powder in the metal bearing liquid an alloy coating such as Pt/Au can be formed. The process may also be used for joining ceramic to ceramic or metal, the dispersion being interposed between the parts and then sintered.  Specifications 878,821 and 878,822 are referred to.ALSO:A metallic or ceramic base is coated with a Pt group metal by applying the coating as a suspension of the flake metal powder in a liquid which will volatilize or decompose under heat and sintering the coating.  The metal base may be stainless steel, Cr, Ni, Mo, Nb, Re, W, Ta, or Ti, and the ceramic may be alumina either glazed or unglazed or zirconia.  The liquid dispersant may be water or preferably a resin dissolved in an organic solvent, such as a solution of condensed methyl cyclohexane polymer in 2-ethoxy ethanol, diacetone alcohol or 2-ethoxy acetate, or it may be a metal bearing liquid such as the liquid bright metals containing Pt, Au or Ag, e.g. gold tertiary dodecyl mercaptan. The dispersion may also contain glass powder which helps the bonding of the metal flake to the ceramic base.  Specifications 878,821 and 878,822 are referred to.